The present disclosure relates generally to medical sensors and, more particularly, to a sensor which self-adjusts and optimizes contact pressure at a sensing site to accommodate for variations in applied pressures resulting in reduced incidents of tissue damage while improving sensor signal quality.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of healthcare, caregivers (e.g., doctors and other healthcare professionals) often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of monitoring devices have been developed for monitoring many such physiological characteristics. These monitoring devices often provide doctors and other healthcare personnel with information that facilitates provision of the best possible healthcare for their patients. As a result, such monitoring devices have become a fixture of modern medicine.
One technique for monitoring physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximeters may be used to measure and monitor various blood characteristics of a patient. For example, a pulse oximeter may be utilized to monitor the blood oxygen saturation of hemoglobin in arterial blood, the relative change in volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. In fact, the “pulse” in pulse oximetry refers to the time-varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximeters typically utilize a non-invasive sensor that transmits light into a patient's tissue and that photoelectrically detects the transmitted and/or scattered light in such tissue. A photo-plethysmographic waveform, which corresponds to the cyclic attenuation of optical energy through the patient's tissue, may be generated from the detected light. Additionally, one or more of the above physiological characteristics may be calculated based generally upon the amount of light transmitted or scattered. More specifically, the light passed through the tissue may be selected to be of one or more wavelengths that may be absorbed or scattered by the blood in an amount correlative to the amount of the blood constituent present in the blood. The amount of light transmitted and/or scattered may then be used to estimate the amount of blood constituent in the tissue using various algorithms.
Inaccuracies in physiological measurements may occur due to improper application of a sensor to a patient. For example, if a sensor is wrapped too tightly around a patient's digit, pressure from the sensor may exsanguinate the tissue at the sensor site such that blood flow through the tissue is reduced. If blood is not allowed to flow normally through the sensor site due to the pressure applied by the sensor, readings from the sensor may be compromised. In addition, excessive localized pressure points between the sensing components and the patient's tissue over an extended time duration can result in pressure sores.
Further, if the sensor is applied loosely to the tissue, other types of inaccuracy may result. For example, if the sensor is too loose, i.e., the sensing components are not held with sufficient pressure against the tissue to ensure proper contact, light shunting may occur where the light transmitted by the emitting component reaches the detector component without passing through the patient's tissue. In some circumstances where the sensor is loose, excessive ambient light from the environment, i.e., light not emitted by the light emitting components of the sensor, may also reach the detector on the sensor, thereby compromising sensor performance. Thus, proper contact between the sensing components and the patient's tissue may be desirable.
In the course of patient monitoring, careful attention by the clinician to apply the sensor with the appropriate applied pressure to ensure proper contact between the sensing components and the patient's tissue, without resulting in excessive localized pressure, can be time consuming. This invention allows the sensor to operate appropriately under a wider range of sensor application pressures by improving the sensor performance while reducing the incidents of excessive localized pressures.